In the above paper, which appeared in the Journal of Geophysical Research, 98(D8), pages 14,753--14,770, August 20, 1993, the caption for Figure 6 should read The change of the trend of methane at Cape Meares. The moving trends are plotted for various ''averaging'' periods. The slopes of the concentration data from time T+j to T+j+Δ are calculated by a linear regression model, where j=0 to N-Δ, N is the number of data, number of months, or number of days in the data set as appropriate. (a) The period over which the trends are calculated is 8 years, (b) the period is 6 years, (c) the period is 5 years, and (d) the period is 3 years. Solid lines are based on daily data; circles are from monthly-averaged data.